开源协议：The Unlicense，可以任意使用。 lib目录下，各库各自协议。
|Parameter||Required or Optional||Description|
|data||Required||The data must be UTF-8 URL-encoded. Note that URLs have a 2K maximum length, so if you want to encode more than 2K bytes (minus the other URL characters), you will have to send your data using POST.
Maximum character storage capacity:984,all data will be encoded in UTF-8.
|size||Optional||The size of each box.
The minimum value is 1, each box has only one pixel, and then shrink will not be able to scan.
The maximum value is 64, each box has 64 pixels. Image size is determined by the data.
The default value is 4, is the most common size.
|ecl||Optional||error_correction_level - QR codes support four levels of error correction to enable recovery of missing,misread, or obscured data.Greater redundancy is achieved at the cost of being able to store less data. Here are the supported values: